Rust repair

[Bait_drifta]

Hey guys, Doing some yearly maintenance on the boat trailer. I have a couple cross members ( the usual suspects) starting to rust. 

  I have a couple questions on repairing with rust  converter.

What rust converter do people recommend?

Can you cold gal over it once converted?

And is there a hack to getting the rust converter into The cross member via the gal hole at the bottom of the cross member? 
 
Any help would be appreciated cheers.

[slowjigger]

Cold gal is meant to go onto bare metal. If you are going to use rust converter then I would use a good quality paint, oil based or epoxy.

Edited July 26, 2023 by slowjigger

[noelm]

Near impossible to clean rust off a trailer, cold gal is near useless if it’s going in the water, it’s barely OK on things just near the water, sorry to say…..

[dunc333]

hi drifta the cross members as you are probably aware rust from the inside out so treating the outside is like putting a bandaid over the .problem. i usually replace cross member or build   a 60mm by 10mm by 1000mm strengher with ubolts to give piece of mind before renewing trailer or  cross member replacement to get by.Any new gal trailer i have i turn upside down and fill up with sump oil and then block drain holes and then will not rust from the inside out  cheers dunc .333.

[frankS]

In days gone by when I worked on trailers often I adapted a tool to fit a 4" grinder that had a 18" arm fitted with emery paper. I had to cut away a section of the bottom of the Xmember and grind away the rust on the inside of the Xmember, This would only do 18" from either side of the centre of the Xmember but it was usually enough, when I ground the rust away I would coat the inside of the Xmember with cold gal using a stick with a rag wrapped around it as a brush. Then when all dry I would weld the section I cut out back in place.

This would give the trailer several more years of service.

Never had one come back to me for warranty so it must have worked.

You could do the same using chisels and sticks etc. But to be honest it's probably easier and quicker to just replace the whole Xmember.

I don't like rust converter.

Frank

[Fab1]

Cutting off cross members and welding new ones on will still rust at the welds both inside and outside.

Any time you grind, cut, weld anything galvanised it will rust as you’ve compromised the galvanisation unless you get it re-galvanised again.( You should always remove galvanisation prior to welding and don’t breath in the fumes).

personally I would cut the cross members off and make new galvanised bolt on ones.

 

Remember rust converter can’t magically put metal back.

I would invest the money you are going to spend on bandaids like cold gal, rust converter on a used/new trailer or replacing the cross members like I mentioned.

Any photos of rusty trailer? Remember the outside will look better than the inside.

[Bait_drifta]

On 7/26/2023 at 7:22 PM, slowjigger said:

Cold gal is meant to go onto bare metal. If you are going to use rust converter then I would use a good quality paint, oil based or epoxy.

Oh ok I wasn’t sure, thanks for the help!

[Bait_drifta]

On 7/26/2023 at 7:33 PM, noelm said:

Near impossible to clean rust off a trailer, cold gal is near useless if it’s going in the water, it’s barely OK on things just near the water, sorry to say…..

I’m just trying to prolong the trailer for alittle while  longer….once the rust starts it almost game over. 

[Bait_drifta]

On 7/26/2023 at 8:27 PM, dunc333 said:

hi drifta the cross members as you are probably aware rust from the inside out so treating the outside is like putting a bandaid over the .problem. i usually replace cross member or build   a 60mm by 10mm by 1000mm strengher with ubolts to give piece of mind before renewing trailer or  cross member replacement to get by.Any new gal trailer i have i turn upside down and fill up with sump oil and then block drain holes and then will not rust from the inside out  cheers dunc .333.

Hey dunc333 , yep Unfortunately when it’s in the cross member it’s impossible to get out. They don’t make them salt water friendly. Thats not a bad idea to strengthen it for the time being until I can get properly fixed. I have heard of the sump oil trick and will be doing it any new trailers down the track or once this one get a redo. Thanks for your help! 

[Bait_drifta]

On 7/27/2023 at 9:30 AM, frankS said:

In days gone by when I worked on trailers often I adapted a tool to fit a 4" grinder that had a 18" arm fitted with emery paper. I had to cut away a section of the bottom of the Xmember and grind away the rust on the inside of the Xmember, This would only do 18" from either side of the centre of the Xmember but it was usually enough, when I ground the rust away I would coat the inside of the Xmember with cold gal using a stick with a rag wrapped around it as a brush. Then when all dry I would weld the section I cut out back in place.

This would give the trailer several more years of service.

Never had one come back to me for warranty so it must have worked.

You could do the same using chisels and sticks etc. But to be honest it's probably easier and quicker to just replace the whole Xmember.

I don't like rust converter.

Frank

Cutting  the cross members out the 100% way to go and start fresh. But atm I not able to, so  I hoping to prolong the trailer for alittle while longer and treat the areas of concern. I was going to spray rust converter inside the cross member using a flexible extension on the spray head to at least try and save it abit, it’s only a band-Aid solution I know but something better then nothing right?! . Thanks for the help frank.

[Fab1]

As for rust conversion….I used phosphoric acid when I was painting cars.I’m assuming there’s many brands of rust converter around these days.The one I used was called Deoxidine.

[Bait_drifta]

16 hours ago, Fab1 said:

Cutting off cross members and welding new ones on will still rust at the welds both inside and outside.

Any time you grind, cut, weld anything galvanised it will rust as you’ve compromised the galvanisation unless you get it re-galvanised again.( You should always remove galvanisation prior to welding and don’t breath in the fumes).

personally I would cut the cross members off and make new galvanised bolt on ones.

 

Remember rust converter can’t magically put metal back.

I would invest the money you are going to spend on bandaids like cold gal, rust converter on a used/new trailer or replacing the cross members like I mentioned.

Any photos of rusty trailer? Remember the outside will look better than the inside.

Getting new cross members on it s the way to go and then get it either acid bathed or sand blasted to remove all the old gal off and get it hot gal again. But atm I can’t it done so I just was hoping to prolong the trailer for alittle while longer.

bolts ones ones could make easier to place when signs of rust are starting to show why done trailer makers done this?! Or put in c sections inside so it’s much easier to clean and maintain. 

Here are the areas of concern Fab1 

[Bait_drifta]

7 minutes ago, Fab1 said:

As for rust conversion….I used phosphoric acid when I was painting cars.I’m assuming there’s many brands of rust converter around these days.The one I used was called Deoxidine.

Thanks, I’ll  check it out! 

[Fab1]

7 minutes ago, Bait_drifta said:

Getting new cross members on it s the way to go and then get it either acid bathed or sand blasted to remove all the old gal off and get it hot gal again. But atm I can’t it done so I just was hoping to prolong the trailer for alittle while longer.

bolts ones ones could make easier to place when signs of rust are starting to show why done trailer makers done this?! Or put in c sections inside so it’s much easier to clean and maintain. 

Here are the areas of concern Fab1 

Can you weld or get what I’m going to tell you welded up?

[Bait_drifta]

5 minutes ago, Fab1 said:

Can you weld or get what I’m going to tell you welded up?

I could get something sorted out, what do you have in mind ? 

[Fab1]

9 minutes ago, Bait_drifta said:

I could get something sorted out, what do you have in mind ? 

- I would start by removing roller cradle and locking bolts.

-Cut off the rusted piece of rhs for roller cradle locking bolt.

-Then brush on hydrochloric acid straight to rusty areas.(You can dilute it 5 parts water to 1 acid and make it stronger as needed if you like). I don’t muck around and use it straight.

 

Make sure you wear a mask, gloves, long sleeves ,goggles and don’t splash it on anything you don’t want eaten away) You’ll see the rust get eaten away in front of your eyes as it fizzes turning a mustard yellow.

 

-When you see all the rust eaten away you’ll need to neutralise the acid with lots of fresh water(use the hose) and wash it all off really well.

- After drying trailer weld plates on top and bottom of cross members and weld on new piece of rhs for roller cradle locking bolt(don’t forget to drill it and weld a suitable nut on) 

- Spray  some etch primer and primer on the area and after it’s dry spray the lot with underbody sealer.

This will make it stronger and last that little bit longer but remember it will still be continuing to rust from inside out.

[Fab1]

45 minutes ago, Bait_drifta said:

Getting new cross members on it s the way to go and then get it either acid bathed or sand blasted to remove all the old gal off and get it hot gal again. But atm I can’t it done so I just was hoping to prolong the trailer for alittle while longer.

bolts ones ones could make easier to place when signs of rust are starting to show why done trailer makers done this?! Or put in c sections inside so it’s much easier to clean and maintain. 

Here are the areas of concern Fab1 

Trailer manufacturers care about sales mate.The quicker your trailer rusts the quicker you come back and give them your $$$$$.

[Fab1]

@Bait_drifta The bottom of my shed was rusted worse than your trailer with holes right through it from the dirt in the garden bed.

I sanded, applied acid, puttied holes, etched primed, primed and sprayed underbody spray over area.I just need to paint it now and it will outlive me.

basically you are doing that to your trailer.

[Bait_drifta]

Thanks for help @Fab1 really appreciate it. I said sand, washed and converted it today and apply one coat of epoxy paint. Looks better already!  hopefully I can get a couple more seasons out of it. Next week going to spray converter inside the cross members to try on prolong them. 

also looking into getting them replaced with potentially bolt on ones. 

[Fab1]

26 minutes ago, Bait_drifta said:

Thanks for help @Fab1 really appreciate it. I said sand, washed and converted it today and apply one coat of epoxy paint. Looks better already!  hopefully I can get a couple more seasons out of it. Next week going to spray converter inside the cross members to try on prolong them. 

also looking into getting them replaced with potentially bolt on ones. 

Good stuff mate.Remember what you did will be temporary.It’s a no brainer for me to go bolt on all the way.